There is a great need for energy efficient radiation sources which will perform multiple tasks according to the program needs. Currently in common use are radiation sources with low energy efficiency such as, incandescent lamps. The luminous efficiency of these lamps are no greater than 5% which means that 95% of the energy produced by these lamps is heat. Heat, in most applications, is not welcome. Particularly excessive heat is not needed in summertime or in countries with warmer climates. Animal farms in warmer climates are adversely affected by the lack of energy efficient electromagnetic radiation sources. Electromagnetic radiation is needed in animal farms to keep animals sterile and in sterile/odorless conditions. The excessive heat often kills animals in spite of very extensive ventilation in brooders or other facilities. Other dangers in animal farms are diseases, such as animal flu, that occurs more often in the presence of excessive heat and humidity.
In the last several years, an enormous effort has been made in the development of highly-efficient energy radiation sources, particularly related to electromagnetic radiation sources. Significant progress has been made in the development of highly efficient light emitting diodes (LEDs) whose luminous efficiency is at least twice better than incandescent lamps. LEDs are also much longer lasting light sources than incandescent lamps; therefore modern LEDs are successfully replacing lamps in traffic lights, cars, and medical devices. LEDs could also be applied in many areas of our lives, however there are still limitations in this technology. One of the limitations is the availability of LEDs of different colors. Only recently were ultraviolet LEDs demonstrated, and still there is a lack of LEDs in the far-infrared spectral range. Another continuing limitation of LED technology is their luminous efficiency. Recent advances in LED technology with organic light emitting diodes (OLEDs) show promise for brighter light sources, however there still is a question if the efforts in the development of OLEDs will be focused only on white OLEDs or will super-bright ultraviolet and infrared OLEDs also be developed. Currently, LEDs are applied successfully in dermatology for removal of acne and wrinkles, which is performed with blue and yellow LEDs respectively. Red LEDs are also used to reduce muscle pain and to increase collagen content in body. However, there are still limitations in the use of LEDs, such as using them for sterilization or as broad-band sources of illumination from UV to far-infrared. The energy efficiency of LEDs continues to require improvement in order to use them as a cost-effective choice.